A great number of offshore wind structures are supported and anchored into the soil under the seabed level through different types of foundations such as pile structures. Pile structures may be of the monopole type or they may comprise smaller diameter piles which are used depending on the specific support structure and soil conditions at the wind farm site.
Handling of wind turbine parts such as the piles and other structures in offshore applications is cumbersome and represents significant costs. Costs involved by handling operations are increasingly higher due to the huge size of current wind turbines which require greater foundations. In addition, said handling operations are unsafe.
Piles are usually transported from a base port to an installation site by vessels. This often requires the use of complex equipment such as large vessels, pile grippers and cranes. All of this involves very high day rates.
It is also known in the art towing wind turbine parts, such as for example piles, for transportation in the sea. Transportation of piles, or other parts, by towing, requires thorough analysis, fulfillment of requirements and respect for restrictions linked to transport speed and weather conditions. These operations also require auxiliary equipment and structures. For example, the parts to be transported on the sea are designed to include internal or external compartments or floating members to provide floating stability on the sea. Specifically, pile transport and installation operations involve potentially risky operations associated with the complex auxiliary equipment and structures required. For example, transportation and installation means and parts often include large dynamically positioned or jack-up vessels, high capacity cranes, ample deck space for storage and manipulation, auxiliary vessels such as tugs, barges or supply vessels, auxiliary equipment like pile grippers, inserts or lifting openings and lugs or plugs that may be removed off the compartments.
The use of floating members is disclosed, for example, in EP2318701 which provides a method of transportation of a floating wind turbine. The method consists in towing a wind turbine by means of a floating member that is attached to the wind turbine. This method involves positioning the wind turbine in an inclined position for being towed. This results in that the process is conducted under unstable working conditions with associated restrictions and risks.
There is thus a need for safe means for the transportation of wind turbine parts through a simple and cost effective global, integrated solution, not only for transporting wind turbine parts from a base port to a wind farm site but upending and installation of the parts and even temporarily supporting them prior to piling to some depth.